photochamber-webserver/static/public/js/chronology.js

$(() => {
    var _MIN = _MAX = null;
    window.chronology = {};

    function onChronologyUpdated() {
        console.log("Chronology update with ", _MIN, _MAX);
    }

    window.chronology.rebuildRange = function(_minTs, _maxTs) {
        let updated = false;

        if (!_MIN || _MIN.getTime() !== _minTs) {
            _MIN = new Date(_minTs);
            updated = true;
        }
        if (!_MAX || _MAX.getTime() !== _maxTs) {
            _MAX = new Date(_maxTs);
            updated = true;
        }
        if (updated)
            onChronologyUpdated();
    }

    window.chronology.isInitialized = function() {
        return _MIN && _MAX;
    }

});